<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <script crossorigin src="https://unpkg.com/react@18/umd/react.development.js"></script>
    <script crossorigin src="https://unpkg.com/react-dom@18/umd/react-dom.development.js"></script>
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
    <title>Document</title>
</head>
<body>
    <div id="root"></div>
    <script type="text/babel">
        
      class Root extends React.Component
        {
            constructor()
            {
                super();
                this.state = {
                    counter:0,
                }
                this.Increment = this.Increment.bind(this);
                this.Decrement = this.Decrement.bind(this);
            }

            render()
            {
                return (
                   <div>
                      <div> {this.state.counter}</div>
                      <button onClick={this.Increment}>+1</button>
                      <button onClick={this.Decrement}>-1</button>
                   </div>
                )  
            }

            Increment()
            {
                this.setState(
                    {
                        counter:this.state.counter+1
                    }
                )
            }
            Decrement()
            {
                this.setState(
                    {
                        counter:this.state.counter-1
                    }
                )
            }
        }
        const root = ReactDOM.createRoot(document.querySelector("#root"));
        root.render(<Root/>);
    </script>
</body>
</html>